1. Field of the Invention
The present invention is directed toward metal casting processes and, more particularly, toward a method and device for recovering and recycling die lubrication used in such metal casting processes.
2. Description of Related Art
In metal casting applications, it is common practice to spray lubricating agents on the dies to cool the dies and to assist in releasing the cast part from the dies. The lubricating or release agents are diluted with water to varying degrees depending upon the part being made and the specific problem being addressed. For example, a normal ratio of water to lubricant may be about 70:1, and a ratio of water to release agent of 25:1 may be used in situations wherein the molded material sticks to the die, etc. Different ratios may also be used on the same die, wherein more lubrication is applied to problematic areas, typically to locations experiencing heat build up due to the configuration of the die. Moreover, individual dies may have multiple sprays sequentially applied thereto at different times during the casting process.
With reference to FIG. 4, a conventional die lubrication system 10 is illustrated to include a pressure intensifier 12, a die lube source 14, a die spray device 16, and a used die lube collection pan 18. The die lube source 14 is fluidly connected, via a pipe 20, a manually operated shut-off valve 21, and an inlet check valve 22, to the pressurizing cylinder 24 of the pressure intensifier 12. Controlled application of a hydraulic source 26 to the master piston 28 of the pressure intensifier moves the piston up and down to selectively draw die lube past the inlet check valve 22 and into the pressure intensifier pressurizing cylinder 24 and then expel pressurized die lube from the pressure intensifier pressurizing cylinder. Pressurized die lube flows through an outlet pipe 30 and outlet check valve 32 to the die spray device 16. The used die lube is collected in the collection pan 18 and directed to the drain 34 and, ultimately, to the plant wastewater treatment facility.
Unfortunately, this common practice is wasteful of die lube, which is relatively expensive and may be used many times if separated from contaminants. Moreover, the processing of waste die lube is a major source of the manufacturing facility waste treatment load. Therefore, there exists a need in the art for a method and device for cleaning and reusing die lube.
The present invention is directed toward a method and device for cleaning and reusing die lube.
In accordance with the present invention, a die lube recovery system includes a weir tank, an oil skimmer, a recovery pump, a filtration assembly, and a holding tank. The weir tank receives used die lube and includes means to filter large particles from the used die lube. The oil skimmer is associated with the weir tank and is operable to remove oil from the used die lubrication.
In further accordance with the present invention, the filtration assembly removes particulates from the used die lube output from the weir tank and supplies reconditioned die lube to the holding tank. The recovery pump forces fluid from an outlet of the weir tank to an input of the filtration assembly.
In further accordance with the present invention, the holding tank contains a quantity of reconditioned die lube and has a first sensor for monitoring a liquid level in the holding tank. When a sensed level of reconditioned die lube in the holding tank falls below a first predetermined level, fresh die lube is added to the holding tank.
The system according to the present invention farther includes a fresh die lube source, a die lube pressure booster, and a die spraying device. The die lube source is fluidly connected, via a pipe and an automatically-operated valve, to the holding tank such that, when the sensed level of reconditioned die lube falls below the predetermined level, the automatically-operated valve is opened to permit fresh die lube to flow into the holding tank.